Method of converting heavy hydrocarbons into lighter hydrocarbons



March 14, 1.933. AEHARNSBERGER ETAL 1,901,593

METHOD OF CONVERTING HEAVY HYDROCARBONS- INTO LIGHTER HYDROCARBONS Filed Nov. 15, 1929 gwue/nto'z ai'lzsbeiyer,

- Patented Mar. 14, 1933 UNITED STATES VPATENT OFFICE AUDLEY E. HARNSBEIRGE R AND CLYDE L. SMITH OF CHICAGO, ILLINOIS, ASIGNORS 'ro GYRO rnocnss rem ' METHOD or ooitvERrm'G HEAVY HYnRocARBoNs INTO LIGHTER rrznreocARBoNs Application filed November 15, 1929. Seriaf No. 407,534.

This invention relates to improvementsin the cracking of the heavier fractions of hytion is maintained at high temperatures and in the vapor phase and wherein provision is made for attaining high yields of the desired lighter oils and, conversely, small yields of heavy residual oils.'

It is a object of the present invention to utilize to a greater extent the self contained heat present in the highly heated vapors which are discharged from converters where- -in oil is cracked in the vapor phase.

It is another object of the invention to introduce into cracked petroleum vapors directly discharged from a cracking zone regulated quantities of a heavy oil having approximately the specific gravity of fuel oil in order that the cracked vapors at a temperature in excess of 1000 F. may through heat interchange with the fuel oil fraction produce or effect a substantial degree of cracking of the fuel oil fraction whereby through this method of operation there is obtained cracking of a heavy fuel oil fraction which heretofore has been put to less valuable or economic uses. y

In accordance with the present invention a selected charging stock is first subjected to vaporizing temperatures wherein a considerable proportion of the stock is vaporized "without any appreciable cracking. The heated oils are then lead to an evaporator wherein takes place a separation. of the light volatile oils as vapors from the heavier liquid oils. The vaporized oils are then passed through a highly heated conversion zone and while in the vapor phase are heated to crack ing temperatures in excess of 1000 Fl until I a desired degree of conversion has taken place. The converted vapors are then directly passed into a closed vessel and in said vessel are brought into contact with the heavy liquid oil. obtained from thebottom of the evaporator in order that through this heat interchange the cracked vapors will be re- COMPANY, OF DETROIT, MICHIGAN, A. CORPORATION OF MICH- duced to a lower temperature. and the heavy liquld oil fraction raised to a suflicient crackv ing temperature. The oils which remain in vaporous form in said supplemental cracking vessel are then led to a conversion arrester where such vapors are brought into contact with a large body of cold oil forced -into the vapors in sufficient quantities to effect theirsudden drop in temperature to a non-convertingtemperature not in excess of 600 F., but not sufficiently low' to prevent fractionation of said vapors without the addition of extraneously supplied heat, the said vapors being then fractionated and condensed as motor fuel distillate, while the heavy oil fractions remain in the liquid form in thelbottom of the supplemental cracking ,vessel or vessels and are separately with drawn from the system as fuel oil.

Heretofore the liquid oil discharged from the evaporator disclosed between the vaporizing and conversion zones has been permanently removed from cracking systems as fuel oil, but by the employment of the resent invention this heavy liquid oil is sub ected to a second heating step at temperatures higher than those which exist in the vaporizing zone,

to the end that all of the low boiling compounds may be extracted from the fuel oil as is possible under practical operating conditions so that the system may produce a high yield of lowboiling compounds with a correspondingly small yield of high boiling fractions or fuel oils which have a much smaller economic value.

For a further understanding of the invention, reference is to be hadto the accompanying drawing wherein is set forth diagrammatically apparatus used in carrying v the present invention into effect.

Referring more particularly to the drawing, the numeral 1 designates a tank adapted for the reception of the oil comprising the charging stock which is fed tothe system. Usually this charging stock consists of a light gas-oil fraction obtained from crude oil fol lowing the topping of such crude oil to remove the gasoline and kerosene fractions, al-

though, if desired, crude oil may be fed direct:

resorting to the customary topping operations.

Leading from the tank 1 is a pipe line 2 in which is positioned a pump 3 through which the charging stock is forced under pressure is forced into the arrester 4: in quantities suf ficient so that through heat interchange with the vapors the temperature of the latter will be reduced sharply and practically instantaneously to a non-converting or reacting temperature not in excess of 600 F. This step is of importance in efi'ecting the matter of minimizing carbon deposition within the arrester 4.

Liquid oils are withdrawn from the bottom of the arrester 4 by way of a pipe line 6, and transferred to the bottom of a fractionating tower 7 The vapors which accumulate in the arrester 4 are passed by an overhead pipe line 8 from thearrester to an intermediate point in the height of the tower 7, and are there subjected to fractionationin 'a customary operation. The vapors released from the top of the fractionating tower pass by way of a pipe line 9 through a condenser 10 and thence into a separator 11, wherein there takes place a separation of the fixed gas, water, if present, and liquid oils, the latter then flowing through an outlet line 12, a lock box 13 and into a container 14 as motor fuel distillate.

The liquid oil which accumulates in the.

drawn by means of the pumps 15. Ordinarily, this quantity of oil is in excess of that required to replenish thefuel or stock input demands of the system, and this excess hot oil is passed through a pipe line 16 and through suitable heat exchangers .17 back to the working tank 1. The oil required to replenish the system i forced by the pumps 15 through a pipe line 18 and passes through vaporizing coils 19 which are arranged in furnace setting 20. In this passage through thecoils 19 the oil is heated to'a vaporizing temperature of for example, approximately 650 F. in order that its lighter constituents may be vaporized but to avoid excessive temperatures which would tend to produce undesirable cracking of the oil. From this vaporizing zone, afforded by the coils 19, the vaporized oil passes through a line 21 to an evaporator 22 in which unit there takes place a separation of the lighter vaporized oils from the heavy liquid oils. The lighter oils pass by way of an overhead through by vaporizing said liquid or by reducing the same to an easily removed "carbon deposit. a

From the drying coil 25 the liquid-free oil vapors then pass through the converting coils 30 arranged in the converter setting wherein said vapors are heated to adecomposition temperature in excess of 1000 F. While in the coil 30, which constitutes a cracking or conversion zone, the oils are subjected to the desired cracking reactions for a regulated period of time to produce low boiling compounds from the ordinary high boiling; charging stock.

Heretofore the oil vapors upon issuing from the converter at temperatures in excess of 1000 F, have been lead directly into the arrester 4 wherein they have been brought into direct contact with large bodies of sprayed and relatively cool charging stock, introduced into the arrester in quantities suflicient to efiect an immediate reduction in temperature of the vapors to a non-reacting temperature not in excess of 600 F. While this prior method operates to practically pre-' vent the liberation of carbon in the cooling zone of the system following conversion, yet it is the aim of the present invention to utilize to a greater degree, for the economic betterment of the system, the self contained heat present in the oil vapors discharged from the converter. We have found that while some carbon is liberated during the cooling of the vapors to a temperature not below 850 F., yet the amount of carbon liberated can be successfully handled inapparatus designed for its reception without interfering with the continuity of operation of the system, and this discovery enables us to utilize approximately 200 F. of the heat contained in the converted vapors usefully and economically in the operation of the system,

n Thus, the present invention provides sup- I tion of the system in the bottom of the evaporator 22, is, in accordance with the present invention, withdrawn from the bottom of the evaporator by way of a line 35 and is forced through said line by a pump 36 into the tops of the cracking chambers 32, where this heavy liquid oil issues in finely divided spray-like form'from the nozzles or sprayheads 37 and settles or descends toward the bottoms of the chambers 32 in countercurrent relationship to the highly heated ascending converted vapors. Thus-the liquid oil obtained from the evaporator is directly subjected to the temperature of the converter vapors and since the latter possess a temperature at the time of introduction into the chambers 32 in excess of 1000 F. and since the liquid fraction obtained from the bottom of the evaporator possess a temperature of approximately 700 F. at this time the in-. troduction into tlietop of thechambers 32 the effective heat interchange thus secured results in raising the temperature of the heavier fractions to a cracking temperature. While this cracking takes place with some liberation of free carbon, the latter is precipitated into the bottom portions 33 of the supplemental cracking chambers together with heavy liquid oils which remain unvaporized. These heavy oils together with the carbon are withdrawn from the supplemental cracking chambers by an outlet line 38 in which is arranged a filter 39 to remove solids, the liquid oil passing on through the filter to a fuel oil storage tank 40. c

The vaporized oils which possess a temperature of approximately 850 to 900 F.-, are discharged from the tops of the chambers 32 and are led by way ofthe vapor line 5 to the arrester 4, where the vapors are brought into direct contact with the cool oil obtained from the tank l in order that the temperature of the vapors may be sharply and suddenly reduced to a non-reacting temperature not in excess of 600 F. It is imperative to employ sharp cooling. of the converter vapors between 850 F. to 600 F., since if ordinary slow methods of cooling are employed "between these temperatures free carbon is liber-J ated in such quantities that it cannot be adequately cared for in commercial systems of operation. Preferably the oils released in vaporous form from the supplemental cracking chambers possess temperatures in excess of 900 F., in orderthat the quantity of coke deposited in the bottoms of said supplemental cracking chambers may be kept to a minimum. This system of operation possesses the advantage over earlier analogous systems in that the quantity of fuel oil. which is of low commercial value, produced by the present system will be reduced to acomparatively small amount as compared with the total input of charging stock into the system.,

Heretofore the liquid fraction obtained from the bottom of the evaporator has been permanently removed from the system as a fuel oil, but in accordance with the present invention this heavy liquid fraction, which cannot be profitably vaporized in the coils 19 is'passed into direct contact with the highly heated converter vapors as the latter issue directly from the converter.v The countercurrent method of contact provided between the conconveniently removed from the system without disturbing the continuous operation of the latter. The pipe line 35 may include a valved branch line 41 in order that the heavy liquid fraction forced through 'the line 35 may be introduced into the supplemental cracking chambers 32 at such a rate as to ,secure a desired degree of cracking and yet to maintain the temperature conditions above noted. The branch line 41 removes excess quantities of the heavy residual oil from the system. I

1 What is claimed is:

- A process for converting heavy hydrocarbons into lighter hydrocarbons, which comprises continuously passing a stream of such heavy hydrocarbons through a primary heating zone wherein said heavy hydrocarbons are subjected to temperatures suflicient- 1y high to eifect vaporization of the lighter compounds therein without material cracking, then passing such hydrocarbons into a separating zone to" separate the said hydrocarbons into a vaporous fraction and a liquid fraction, continuously passing the vaporous fraction through a highly heated conversion zone wherein the vapors are heated to cracking temperatures in excess of 1000 F., continuously passing the cracked vapors from said conversion zone into a supplemental cracking zone, continuously introducing the liquid fraction obtained from said separa tion zone into direct contact with the cracked oil vapors present in the supplemental cracking zone, controlling the rate of fiow of the liquid fraction into said supplemental cracking zone to permit the self contained heat present in the cracked oil vapors to raise the temperature of said liquid fraction sufliciently to partially crack the same without reducin the temperature of the cracked oil vapors elow 850 F., passing the oil vapors remaining at such latter temperature into a shock chilling zone wherein said vapors are brought into contact with quantities of liqum oil to efl'ect a substantially instantaneous re-' duction in temperature thereof to a non-reacting temperature not in excess of 600 F, 5 and then. fractionating the Vapors present at said latter temperature.

In testimony whereof We afix our signatures.

m AUDLEYE. HARNSBERGER.

' CLYDE 1L. SMITH. 

